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Ideal Gases
1L =1 dm3= 0.001 m3
1L=1000 cm3, cc, mL 1m3 =1000 dm3 =106 cm3
RTVPnRTPV
1
Chapter 16: The Properties of Gases
Gas Constant
2
Real Gases versus Ideal Gases
3
300 K
CH4
Van der Waals, Redlich-Kwong, Peng-Robinson
4
5
6
Van der Waals, Redlich-Kwong, Peng-Robinson
vdw ??
ethane at 400 K
ethane at 305.33 K
7
Experimental P-V isotherms of CO2
8
Cubic Equations of State describe both liquid and gaseous region
9
Critical values of Pc , Vc , and Tc for vwd EOS
Critical values of Pc , Vc , and Tc for R-K EOS
10
27
8 27
3 2 bRaT
baPbV ccc
The value of is constant !!
11
The constant values of EOS can be obtained from Pc and Tc
12
Law of Corresponding States (LOCS)
13
Based on LOCS, all gases have the same functional
14
Virial Equation of State
15
Experimental Determination of B2V
B2V and Temperature
16
Relationships between virial coefficients and intermolecular interactions
r
Lennard-Jones Potential
17
18
Divide both sides by
B2V and LOCS
19
xr/TkT B VH /*
@ T* | 3.2 , B2v (T*) =0
B*2V vs T* and Boyle Temperature
20
The second virial coefficient indicates the first deviation from ideal gas
21
Three contributions to attractive force
22
Hard-Sphere Potential
23
Square-Well Potential
24
Relationship between B2V and a, b coefficients in vdw EOS
25
Relationship between B2V and a, b coefficients in vdw EOS
drreNdrrNTB 2rTkc
A2
A6
B ]1[2 )1(2- )(
0v2
6
³³f
��� V
V
SS 1 / 66 ¢¢rTkc B
36
2
3 2
VS cNa A
32 3
ANb SV
26
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x 1